# US 10,765,456 B2 · Pivotal bone anchor assembly with friction fit pop-on shank > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,765,456 B2 - Document ID: US10765456B2 - Status: Granted - Kind: B2 - Application number: 16/538,443 - Filed: 2019-08-12 - Published: 2019-11-28 - Granted: 2020-09-08 - Earliest claimed: 2009-06-15 - Assignees: Roger P. Jackson - Applicants: Roger P. Jackson - Inventors: Roger P. Jackson; James L. Surber - Web page: https://patentgrep.com/patent/US10765456B2 ## CPC - A61B 17/7037: {wherein pivoting is blocked when the rod is clamped} - A61B 17/7008: {with parts of, or attached to, the longitudinal elements, bearing against an outside of the screw or hook heads, e.g. nuts on threaded rods (A61B17/7007 takes precedence)} - A61B 17/702: {having a core or insert, and a sleeve, whereby a screw or hook can move along the core or in the sleeve} - A61B 17/8605: {Heads, i.e. proximal ends projecting from bone} - A61B 17/8615: {at the central region of the screw head} - A61B 17/864: {hollow, e.g. with socket or cannulated} - A61B 17/8685: {comprising multiple separate parts} - A61B 17/7031: {made wholly or partly of flexible material} - A61B 17/705: {for linking adjacent ends of longitudinal elements} - A61B 17/7091: {for applying, tightening or removing longitudinal element-to-bone anchor locking elements, e.g. caps, set screws, nuts or wedges} - A61B 2090/037: {with a frangible part, e.g. by reduced diameter} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in a receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. The upper portion expands a retaining member in the receiver cavity to capture the shank upper portion in the receiver. In some embodiment either the retaining member or an insert provide for a friction fit of the shank upper portion in the receiver resulting in non-floppy placement of the shank with respect to the receiver. Some retainers and inserts have a lock-and-release feature. Final locking of the polyaxial mechanism is provided by frictional engagement between the shank upper portion and the retaining member. A pre-assembled receiver, retaining member and optional insert may be popped-on or snapped-on to the shank upper portion prior to or after implantation of the shank into a vertebra. ## Claims ### Claim 1 A pivotal bone anchor assembly for securing an elongate rod to a patient bone via a closure, the pivotal bone anchor assembly comprising: a shank having a longitudinal axis, a proximal capture portion, and a unitary anchor portion extending distally from the capture portion and configured for fixation to the patient bone, the capture portion including a first partial spherical outer surface configured for direct frictional engagement with the elongate rod, and a second partial spherical outer surface defining a hemisphere plane at a maximum width perpendicular to the shank longitudinal axis, the second partial spherical outer surface terminating at an annular rim located above the hemisphere plane and below the first partial spherical outer surface; a receiver having a base defining a chamber in communication with a bottom of the receiver through a lower opening, and pair of upright arms extending upwardly from the base to define an upwardly-open channel communicating with the chamber and configured to receive a portion of the elongate rod, the chamber defined in part by a lower seat and in part by an expansion recess located between the lower seat and the channel; and a retainer positionable in the receiver chamber prior to the shank proximal capture portion and configured to expand about the capture portion in the expansion recess of the receiver chamber when the capture portion is uploaded into the receiver chamber through the lower opening, so as to receive, capture and hold the capture portion in the receiver chamber, wherein the retainer is further configured to engage the lower seat of the receiver chamber when the shank is in a frictionally fixed orientation with respect to the receiver. ### Claim 2 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein a radius of the second partial spherical outer surface is greater than a radius of the first partial spherical outer surface. ### Claim 3 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the first partial spherical outer surface includes a shank drive feature formed therein configured for engagement with a shank driving tool. ### Claim 4 (depends on 3) The pivotal bone anchor assembly of claim 3, wherein the shank drive feature further comprises at least one cutout extending downward into the first partial spherical outer surface. ### Claim 5 (depends on 3) The pivotal bone anchor assembly of claim 3, wherein the shank drive feature further comprises at least one concave partial cylindrical surface aligned parallel with the shank longitudinal axis. ### Claim 6 (depends on 3) The pivotal bone anchor assembly of claim 3, wherein the shank drive feature further comprises a plurality of faceted surfaces substantially aligned with the shank longitudinal axis. ### Claim 7 (depends on 1) The pivotal bone anchor assembly of claim 1, further comprising an annular surface extending inward from the annular rim. ### Claim 8 (depends on 1) The pivotal bone anchor assembly of claim 1, further comprising a plurality of concave surface features formed into the annular rim. ### Claim 9 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the receiver chamber expansion recess includes an overlapping surface configured to engage a top surface of the retainer during the uploading the shank proximal capture portion into the receiver chamber through the lower opening, so as to inhibit the retainer from moving upwardly within the expansion recess. ### Claim 10 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the retainer is up-loadable into the receiver chamber through the lower opening. ### Claim 11 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the retainer is non-pivoting with respect to the receiver. ### Claim 12 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the retainer further comprises a split ring. ### Claim 13 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the shank is cannulated along the entire length thereof. ### Claim 14 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the retainer is configured to be positioned within and constrained by the expansion recess prior to up-loading the shank capture portion into the receiver assembly through the lower opening. ### Claim 15 (depends on 14) The pivotal bone anchor assembly of claim 14, wherein the retainer is held in the expansion recess by a resilient structure. ### Claim 16 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the retainer is down-loadable into the receiver chamber through the upwardly-open channel. ### Claim 17 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the retainer includes an internal concave surface that extends above the shank hemisphere plane when the shank capture portion is capture by the retainer in the receiver chamber. ### Claim 18 (depends on 1) The pivotal bone anchor assembly of claim 1, wherein the retainer is configured to provide a friction fit for fixing the shank with respect to the receiver prior to a locking of the assembly via the closure. ### Claim 19 (depends on 1) The pivotal bone anchor assembly of claim 1, further comprising the closure, and wherein the closure includes a splay-resisting helically wound guide and advancement structure configured to rotatably made with a complementary structure formed in the receiver channel.